Add Map<String, bool> return type and method depracation

lib/src/authorization_scope.dart

@@ -54,7 +54,7 @@ class FollowAuthorizationScope extends _Scope {
   /// Read access to the list of artists and other users that the user follows.
   ///
   /// Endpoints that require the `user-follow-read` scope:
-  /// * [Me.isFollowing]
+  /// * [Me.containsFollowing]
   /// * [Me.following]
   String get read => 'user-follow-read';
 
@@ -145,7 +145,7 @@ class LibraryAuthorizationScope extends _Scope {
   /// * [Me.containsSavedEpisodes]
   /// * [Me.savedAlbums]
   /// * [Me.containsSavedAlbums]
-  /// * [TracksMe.contains]
+  /// * [TracksMe.containsTracks]
   /// * [TracksMe.containsOne]
   /// * [TracksMe.saved]
   String get read => 'user-library-read';
@@ -194,7 +194,7 @@ class PlaylistAuthorizationScope extends _Scope {
   /// Read access to user's private playlists.
   ///
   /// Endpoints that require the `playlist-read-private` scope:
-  /// * [Playlists.followedBy]
+  /// * [Playlists.followedByUsers]
   /// * [Playlists.me]
   /// * [Users.playlist]
   String get readPrivate => 'playlist-read-private';

lib/src/endpoints/endpoint_paging.dart

@@ -110,19 +110,19 @@ abstract class NextStrategy<T> {
 /// Strategy to get the next set of elements from an offset
 mixin OffsetStrategy<T> implements NextStrategy<T> {
   @override
-  Future<T> first([int limit = defaultLimit]) => _getPage(limit, 0);
+  Future<T> first([int limit = defaultLimit]) => getPage(limit);
 
   @override
   Future<T> _getPage(int limit, dynamic next) => getPage(limit, next as int);
 
   /// Abstract method that is used to do the api call and json serializing
-  Future<T> getPage(int limit, int offset);
+  Future<T> getPage(int limit, [int offset = 0]);
 }
 
 /// Strategy to get the next set of elements from a cursor
 mixin CursorStrategy<T> implements NextStrategy<T> {
   @override
-  Future<T> first([int limit = defaultLimit]) => _getPage(limit, '');
+  Future<T> first([int limit = defaultLimit]) => getPage(limit);
 
   @override
   Future<T> _getPage(int limit, dynamic next) => getPage(limit, next as String);
@@ -229,7 +229,7 @@ class Pages<T> extends SinglePages<T, Page<T>> with OffsetStrategy<Page<T>> {
   }
 
   @override
-  Future<Page<T>> getPage(int limit, int offset) async {
+  Future<Page<T>> getPage(int limit, [int offset = 0]) async {
     var pathDelimiter = _path.contains('?') ? '&' : '?';
     var newPath = '$_path${pathDelimiter}limit=$limit&offset=$offset';
 
@@ -293,7 +293,7 @@ class BundledPages extends _Pages with OffsetStrategy<List<Page<dynamic>>> {
       : super(api, path, pageKey, pageContainerParser);
 
   @override
-  Future<List<Page<dynamic>>> getPage(int limit, int offset) async {
+  Future<List<Page<dynamic>>> getPage(int limit, [int offset = 0]) async {
     var pathDelimiter = _path.contains('?') ? '&' : '?';
     var path = '$_path${pathDelimiter}limit=$limit&offset=$offset';
 

lib/src/endpoints/me.dart

@@ -25,24 +25,45 @@ class Me extends _MeEndpointBase {
     return User.fromJson(map);
   }
 
-  /// Endpoint /v1/me/following only supports "artist" type at the moment.
-  /// needs 'user-follow-read' scope
-  CursorPages<Artist> following(FollowingType type, [String after = '']) {
+  /// Endpoint `/v1/me/following` only supports [FollowingType.artist]
+  /// at the moment.
+  ///
+  /// Needs `user-follow-read` scope
+  CursorPages<Artist> following(FollowingType type) {
+    assert(
+        type == FollowingType.artist,
+        'Only [FollowingType.artist] supported for now. Check the spotify documentation: '
+        'https://developer.spotify.com/documentation/web-api/reference/get-followed');
     // since 'artists' is the container, there is no
     // containerParse necessary. Adding json to make the
     // CursorPages-Object happy.
     return _getCursorPages('$_path/following?type=${type._key}',
         (json) => Artist.fromJson(json), 'artists', (json) => json);
   }
 
-  /// Check if current user follow the provided artists. The output [bool]
-  /// list is in the same order as the provided artist-id list
-  Future<List<bool>> isFollowing(FollowingType type, List<String> ids) async {
+  /// Check to see if the current user is following one or more artists or
+  /// other Spotify users. The output [bool] list
+  /// is in the same order as the provided artist-id list
+  @Deprecated('Use [spotify.me.checkFollowing(type, ids)] instead')
+  Future<List<bool>> isFollowing(FollowingType type, List<String> ids) async =>
+      (await checkFollowing(type, ids)).values.toList();
+
+  /// Check if current user follow the provided [FollowingType.artist]s or
+  /// [FollowingType.user]s.
+  ///
+  /// Returns the list of [ids] mapped with the response whether it has been
+  /// followed or not
+  Future<Map<String, bool>> checkFollowing(
+      FollowingType type, List<String> ids) async {
     assert(ids.isNotEmpty, 'No user/artist id was provided');
-    final jsonString = await _api._get(
-        '$_path/following/contains?type=${type._key}&ids=${ids.join(",")}');
+
+    final jsonString = await _api._get('$_path/following/contains?' +
+        _buildQuery({
+          'type': type._key,
+          'ids': ids.join(','),
+        }));
     final list = List.castFrom<dynamic, bool>(json.decode(jsonString));
-    return list;
+    return Map.fromIterables(ids, list);
   }
 
   /// Follow provided users/artists\
@@ -207,10 +228,8 @@ class Me extends _MeEndpointBase {
 
   /// Returns the current user's saved episodes. Requires the `user-library-read`
   /// scope.
-  Pages<EpisodeFull> savedEpisodes() {
-    return _getPages(
-        '$_path/episodes', (json) => EpisodeFull.fromJson(json['episode']));
-  }
+  Pages<EpisodeFull> savedEpisodes() => _getPages(
+      '$_path/episodes', (json) => EpisodeFull.fromJson(json['episode']));
 
   /// Saves episodes for the current user. Requires the `user-library-modify`
   /// scope.

lib/src/endpoints/playlists.dart

@@ -292,13 +292,25 @@ class Playlists extends EndpointPaging {
   /// [playlistId] - the playlist ID
   /// [userIds] - the ids of the users
   /// The output List of boolean maps to the order of provided userIds list
+  @Deprecated('Use [followedByUsers(playListId, userIds)] instead')
   Future<List<bool>> followedBy(String playlistId, List<String> userIds) async {
+    return (await followedByUsers(playlistId, userIds)).values.toList();
+  }
+
+  /// check if a playlist is followed by provided users
+  /// [playlistId] - the playlist ID
+  /// [userIds] - the ids of the users
+  ///
+  /// Returns the list of [userIds] mapped with whether they are following or
+  /// not
+  Future<Map<String, bool>> followedByUsers(
+      String playlistId, List<String> userIds) async {
     assert(userIds.isNotEmpty, 'No user id was provided for checking');
     final jsonString = await _api._get(
       'v1/playlists/$playlistId/followers/contains?ids=${userIds.join(",")}',
     );
     final list = List.castFrom<dynamic, bool>(json.decode(jsonString));
-    return list;
+    return Map.fromIterables(userIds, list);
   }
 
   /// Returns the cover images of [playlistId]

lib/src/endpoints/tracks.dart

@@ -58,22 +58,25 @@ class TracksMe extends EndpointPaging {
   }
 
   Future<bool> containsOne(String id) async {
-    final list = await contains([id]);
-    return list.first;
+    final list = await containsTracks([id]);
+    return list[id] ?? false;
   }
 
+  @Deprecated('Use [containsTracks(ids)] instead')
   Future<List<bool>> contains(List<String> ids) async {
+    return (await containsTracks(ids)).values.toList();
+  }
+
+  Future<Map<String, bool>> containsTracks(List<String> ids) async {
     assert(ids.isNotEmpty, 'No track ids were provided');
     final limit = ids.length < 50 ? ids.length : 50;
     final idsParam = ids.sublist(0, limit).join(',');
     final jsonString = await _api._get('$_path/contains?ids=$idsParam');
     final list = List.castFrom<dynamic, bool>(json.decode(jsonString));
-    return list;
+    return Map.fromIterables(ids, list);
   }
 
-  Future<void> saveOne(String id) {
-    return save([id]);
-  }
+  Future<void> saveOne(String id) => save([id]);
 
   Future<void> save(List<String> ids) async {
     assert(ids.isNotEmpty, 'No track ids were provided');

test/data/v1/me/tracks/contains.json

@@ -0,0 +1,5 @@
+[
+  true,
+  false,
+  true
+]

test/data/v1/playlists/1XIAxOGAEK2h4ravpNTmYF/followers/contains.json

@@ -0,0 +1,5 @@
+[
+  true,
+  false,
+  true
+]

test/spotify_test.dart

@@ -186,6 +186,16 @@ Future main() async {
       expect(firstImage.height, 300);
       expect(firstImage.width, 300);
     });
+
+    test('followedByUsers', () async {
+      var result = await spotify.playlists
+          .followedByUsers('1XIAxOGAEK2h4ravpNTmYF', ['1', '2', '3']);
+
+      expect(result.length, 3);
+      expect(result['1'], isTrue);
+      expect(result['2'], isFalse);
+      expect(result['3'], isTrue);
+    });
   });
 
   group('Shows', () {
@@ -309,16 +319,16 @@ Future main() async {
       expect(first.after, '0aV6DOiouImYTqrR5YlIqx');
     });
 
-    test('isFollowing', () async {
-      final result = await spotify.me.isFollowing(FollowingType.artist, [
+    test('checkFollowing', () async {
+      final result = await spotify.me.checkFollowing(FollowingType.artist, [
         '2CIMQHirSU0MQqyYHq0eOx',
         '57dN52uHvrHOxijzpIgu3E',
         '1vCWHaC5f2uS3yhpwWbIA6'
       ]);
       expect(result.isNotEmpty, isTrue);
-      expect(result.first, isTrue);
-      expect(result[1], isFalse);
-      expect(result.last, isTrue);
+      expect(result['2CIMQHirSU0MQqyYHq0eOx'], isTrue);
+      expect(result['57dN52uHvrHOxijzpIgu3E'], isFalse);
+      expect(result['1vCWHaC5f2uS3yhpwWbIA6'], isTrue);
     });
 
     group('me/top', () {
@@ -454,6 +464,17 @@ Future main() async {
     });
   });
 
+  group('Tracks', () {
+    test('containsTracks', () async {
+      var result = await spotify.tracks.me.containsTracks(['1', '2', '3']);
+
+      expect(result.length, 3);
+      expect(result['1'], isTrue);
+      expect(result['2'], isFalse);
+      expect(result['3'], isTrue);
+    });
+  });
+
   group('Auth', () {
     test('getCredentials', () async {
       var result = await spotify.getCredentials();